Tartle is an old Scottish word for the moment of hesitation when you are introducing someone whose name you can’t remember. – WTF Fun Facts
Source: https://www.telegraph.co.uk/culture/books/booknews/7936824/Tartle-bufetak-kaelling-the-foreign-words-to-which-English-has-no-answer.html
WTF Fun Fact – Tartle
